Reflection of Light

When a ray of light falls on any surface, a part of the light is sent back to the same medium. This phenomenon where the incident light falling on a surface is sent back to the same medium is known as reflection.

There are two types of reflection of light:

• Regular reflection

• Irregular reflection

     If we know how light behaves when it is reflected we can use a mirror to change the direction in which the light is traveling. This happens when a mirror is placed at the entrance of a concealed drive to give warning of approaching traffic.

    An ordinary mirror is made by depositing a thin layer of silver on one side of a piece of glass and protecting it with paint. The silver - at the back of the glass - acts as the reflecting traffic.

    From the below explanation we can understand the law of reflection of light.

    Let, we will see about the law of reflection of light.The terms used in connection with reflection are shown in the below figure. The vertical to the mirror at the peak where the incident ray strikes it is called the normal.

    Note that the angle of occurrence i is the angle among the incident beam and the normal; similarly the angle of reflection r is the angle between the reflected ray and the normal.

                                                                                              (Source: Wikipedia)

The above figure shows the reflecting of light by a plane mirror, which is understood by the law of reflection.

The law of reflection states:

The angle of incidence equals the angle of reflection.

The incident beam, the replicate beam and the normal all lie in the equal plane. That is they can all be drawn on a flat sheet of paper.

By the above explanation we can understood the law of reflection of light.

Regular Reflection on a Smooth Surface

Regular reflection takes place when a ray of light is incident on a polished smooth surface like a mirror. Here the reflected ray of light moves only in a fixed direction.

Diffused Reflection on a Rough Surface

Irregular reflection or diffused reflection takes place when a ray of light is incident on a wall or wood, which is not smooth or polished. In this case, the different portions of the surface reflect the incident light in different directions. In such cases no definite image is formed, but the surface becomes visible. It is commonly known as scattering of light. Thus diffused reflection makes non-luminous objects visible.

Not all light, which hits an object, is reflected. Some of the incident light is absorbed. The brightness of an object depends on the intensity of the incident light and also on the reflectivity of the object.

If a surface allows the entire incident light to undergo regular reflection then it will become invisible.